Bicycle frame



FIG. 1 is a front and side perspective view of a bicycle frame, showing my new design;

FIG. 2 is right side view thereof;

FIG. 3 is left side view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom thereof;

FIG. 6 is a front view thereof; and,

FIG. 7 is a back view thereof.

The broken lines shown in the drawing illustrate environmental structure that forms no part of the claimed design. 

The ornamental design for a bicycle frame, as shown and described. 